Loading Open Wire Lines

Loading: Open Wire Versus Cable Applications

Rare photo of storm-guyed structure sporting top arm loading coils (black cases). Note the use of break-irons to dead-end the loop pairs to each metal-cased coil assembly. Original coils were placed in wooden cases and surrounded by air, unlike these above, whose internal parts were oil insulated and cooled. Wood was thought to mitigate the stray magnetic effects leading to possible energy losses. Photo date: shortly after World War I or early 1920s (note automobile style in background). Photo source and location unknown.

Introduction

Many of you have seen the very large cases or “tanks” attached to a pole on a cable route. These are separated from each other by considerable distance. At inspection, the ground viewer will see an exposed cable stub leading from the main aerial lead- or suspended plastic-sheathed cable spliced into the pigtail of the tank-like device. These are “loading coils” and are of various sizes. Some, as were placed on the “A&B” cable between Chicago and Omaha on the transcontinental route, were the size of 50- and 100-kVA electric pole transformers. Their cases were mounted on a two-pole structure with two steel “I” beams between poles. The earlier models were square; the later 1920s and after, round. They could be as small as a couple of inches in diameter and a half foot long.

Loading coils were not placed in series with cable pairs for decoration or to reduce the power to customers. Instead, they were “induction devices,” as regular A. C. distribution transformers, but did several things in regards to telephone D. C. circuit health:

Each installation increases series resistance and inductance of the conductors (pairs).

Placing loading coils into cable circuits increases inductance, thus reduces the speed of voice and carrier currents. In fact, for voice frequency circuits, loading is applied liberally. Unfortunately, for carrier, it deteriorates signals where they operate higher than the cutoff frequency of the loading design.

Now, why talk about cable instead of open wire, for introducing this topic? The principles of loading on telecom voice frequency circuits are well understood today. However, the only load coils seen today are those on cable–aerial, buried or underground. After the mid-1920s, loading was removed from open wire even though initially applied in the early days on some long routes. Today, cables are frequently loaded in many situations. However, the effects of an inductance device such as a load coil on open wire circuits opened significant “cans of worms,” to their efficient operation and evolution. So, while we see multi-pair copper cable lines loaded (POTS), to open wire it is a “No, No!”

Let’s go back in history and review why open wire saw such initial promise with these coils but was quickly removed, and instead, became the standard of quality cable pair operation.

Let’s “Load” Up on the Basics of Attenuation

What is “attenuation?” This, in general, is a five dollar word for interference. Interference on open wire is much less than when confined within a sheath as cable pairs. Cables were instrumental, even in the early days, of allowing open wire signals to be transmitted into central offices (C.O.s) and various repeater huts. Railways, their civilian counterparts in telecom, and other transportation organizations, used cables because they were less exposed to the elements, allowed use of limited clearance and space, and could be buried or placed in underground conduits. Clearly, the cable had a major role to play not just into the future, but even in the early days of open wire applications.

Open wire toll plant, by 1880, had expanded to nearly 50 miles, while its rival, cable in 1883, had expanded to over one quarter mile in Boston. This major initiative was surpassed swiftly by a ten mile cable route between New York and Newark in 1902.

Open wire was rushing west, as an 1893 open wire toll lead furnished daily service between Chicago and New York. This nine-hundred mile link was groundbreaking, but heartbreaking as well, since this appeared to be the longest stretch of line for which speech satisfactorily could extend without impacting fatal electrical losses.

With the application of U. S. Patent 0-652-230, filed on December 14, 1899, by Mihajlo. I. Pupin, the loading coil became practical, however, Pupin only refined the thinking of an earlier scientist, Oliver Heaviside. Heaviside was a brilliant mathematician who advanced calculus to analyze circuit elements. By examining telegraph cables in use, he found there could be ways of increasing inductance, thus emphasizing further efficiencies of operation.

Heaviside sought a “distortionless” transmission line, but found this could only occur if several factors combined. These, he referred to as, “The Heaviside Condition.” Series impedence (Z), must be proportional to the shunt admittance (Y), within all frequencies. No transmission line at that time was characterized by such a perfect situation, because insulators leak (low value) whether they are glass or plastic (in cables). To remedy this situation, Heaviside considered improving inductance by:

wide spacing of each line wire

impregnating the insulators with iron dust

These were rather impractical during the late 1880s, so Heaviside proposed placing spaced inductance devices along the transmission line at regular intervals. This was a remarkable idea, but the powers that be in Britain, didn’t warm to the idea. Because his ideas resided in theory, rather than a practical patented device, his suggestions were politely ignored.

Around the mid-1890s, John S. Stone, an AT&T engineer offered the idea of “continuous loading” analogous to Heaviside’s theories on cable induction, but it never saw direct application. Later elements of his thinking found derivation in other forms of cable manufacture and design.

Where open wire might have stalemated, loading furnished a load of relief to telephone engineers, who now might extend the western toll routes. Soon followed some record achievements following the invention of the loading coil in 1900:

As the H.M.S. Titanic’s construction and preparation for its first and final voyage was ending, 85,000 miles of open wire in the United States was loaded. Cable, too, was loaded to the total of over 170,000 miles. As we have spoken in Song elsewhere about Toll Entrance Cables, we’ll refresh the fact the majority of these loaded cables were inter-office trunk types. At the time, over 125,000 loading coils were then in use.

Use of loading coils in conjunction with the birth of the telephone repeater, made further generous loading of open wire possible. By the 1924 Presidential Election, 200,000 miles of open wire and 135,000 miles of cable were loaded. Added up, over 777,000 loading coils were in use on the Bell System (according to their records) of which half a million coils were on inter-office trunk lines. 1,240,000 Western Electric loading coils were implemented around the various operating companies of the Bell System and its Long Lines Division. This does NOT include the various thousands of Independent companies (as for example in Iowa, where companies numbered over 800 Independents!) using loading on their smaller systems where exchange and short distance toll were efficiently applied and activated. Sounded like a good cause should go on . . . forever . . . right?

So, why did loading remain on cable and removed from open wire beginning in 1926? Let’s look at the basics of cables vs. aerial wire. If you go to the section on Aerial Toll Lead Obituaries, you’ll find a cross-section of the original A&B Cable used from Chicago to Omaha replacing the original open wire in 1936. In your neighborhood, spot an aerial cable and if you cut it open, clearly exposed will be different insulated-colored conductors. Typically, such cables contain either: 19-, 22-, 24-, or 26-guage conductors. Obviously, these are quite small gauges. As they become more distant from the C. O. or RST or RT (Remote Subscriber Terminal) their size diameter increases.

However, with toll cables, where some distance passes between town to town, two pairs with identical electrical characteristics are transposed (twisted pairs) forming a four-wire group, or “quad.” They are directional; meaning one pair transmits one direction “East” while the other “West.” You’ll find it referred to as the “four-wire circuit” and carrier is most often utilized on these pairs.

Capacitors are created when an insulator separates to conductive materials and electricity is applied. Aerial copper open wire pairs are no different. The two wires (and on large toll leads) the pairs above, below and beside them, perform this effect, as conductors are separated by an insulator–air. So if the lead is a long one, capacitance increases. Great insulators lessen capacitance and poor ones result in greater degrees of capacitance.

Cable circuits suffer far greater attenuation, or interference losses, than open wire for a multitude of practical and important reasons. When you combine multiple pairs so densely packed in one sheath, higher attenuation results. Now, if we introduce carrier, with its higher frequencies, then losses skyrocket. But first things first . . .

You ask, “But wasn’t carrier first developed for open wire?” Yes, it was. Development of open wire carrier led to the use of impedance-matched carrier systems for cable. However, loading coils tended to block higher frequencies, as were used in open wire carrier. Also, higher speed telemetry circuits experienced problems with loaded circuits. When a long-haul open wire circuit was loaded, even under perfect conditions, the transmission velocity was substantially slowed. One major issue with these open wire long lines were the echo effects. While echo cancelers were applied later to toll cable, the advance of carrier on toll carrier essentially rendered the loading coil unnecessary on lengthy routes. Suburban and exchange carrier yet use them, but their use is decreasing.

Clearly, cables were shown to have higher losses than open wire lines. While attempting to reduce distributed resistance by increasing the size of the cross-section of the metallic pair, might work (and does), now you have a very weighty cable and fewer pairs contained within the same sized sheath. This impractical improvement has its benefits: distributed capacitance is cut by increasing space between them and in turn decreases capacitance along the whole run of the cable, too. However, instead of a 300-pair cable along an expensive ROW/easement, you’ve got a far less efficient by-way for telecom. Remember: in telecom traffic efficiency is number one priority.

For example, if loading coils had never been placed in the early years within the outside plant investment of long distance communications companies and larger diameter conductors were to take their place, it is estimated that the plant investment by 1930 would have been greater than one third of a billion dollars! Think of the open wire facilities! Using 16-gauge conductors, for example, would make crossarm mechanical stability necessary. This would require heavier pins and arms. Lots of costs pile up there.

What is the alternative to this “fewer pairs are better” arrangement? Loading. By increasing distributed inductance, attenuation is cut significantly. What loading does is convert a cable with certain negative characteristics to one with improved electrical characteristics. The word which is most important is “constant.” Loading in voice frequency cable pairs allows the entire per-unit length to be static; predictable in quality throughout. Between the various voice frequencies, there can be a maximum transfer of power, because loading is undertaken.

Now, open wire lines . . . don’t have the significant losses, or attenuation which cram-packed copper cable pairs experience. Yes, there are losses, but are quite different and vary over time. We talked about “constant” electrical characteristics of multi-pair cable with loading. But, open wire is not protected within a sheath and therein lies the problem. Exposed to the open air, these typically uninsulated conductors suffer the vagaries of climate: rain, sleet, snow (wet snow conducts; dry snow acts as an insulator), wind (which pitches the separation of pairs from one another as well as deflecting them at points of contact with insulators), pairs hung above and beneath other circuits as well as electric power A.C. potential induction and contact, simply do not allow open wire to be loaded.

Here’s another peril: loading coils are impractical to increase open wire’s inductance as an efficiency method because we know how wet insulators impact attenuation–especially at higher frequencies–and no insulator is completely an “insulator”. All have leakage losses of one form or another. This bouncing “imbalance” between electrical characteristics versus cable pairs protected within a sheath, make loading really pretty impractical.

Another feature restricting their use on open wire was the reduction in line distortion effects. To explain, loading open wire revealed the need for far better insulators at each pole attachment along with new procedures where separation between physical pairs was crucial. A loaded line worked at higher voltage than non-loaded. Because all insulators “leak,” there is a propensity for all insulators to shed a little voltage over their sides down to the pin and arm and to the pole when it rains. Other contaminates also worked vengeance on open wire, such as dust, salt spray from the oceans and industrial pollution. Steam trains were major perpetrators of the latter with their exhaust of black smoke billowing from their engine stacks and depositing upon insulators, un-insulated tie wires and crossarm pins.

When the U. S. Transcontinental (original) link was being constructed in the early teens of the 20th Century, loading open wire furnished enough “umph!” to make transmission efficiency capable from New York to Denver. However, loading open wire was substantially different than the existing cable lines at the time.

Open wire was loaded, but distances between loading coils was far closer making these aerial pairs very heavily loaded. Also, as in this chapter heading photograph, the load coil cases were large, so they could accommodate very large coils–much bigger than cable’s similarly installed units.

Open wire was much more susceptible to lightning attack than cable, thus they had a “breakdown” test strength at the early part of the last century at 8-kV. Each coil was protected with lightning arresters on each side pair.

Also open wire, which in early use, was considered far more efficient at voice transmission than cable. That suggested to the experts at that early date, the need for open wire loading coils to have smaller losses than underground cable coils was required.

Interestingly enough, however, transmission delay effects are quite remarkable. Over cable, voice waves are slower than open wire leads. Long distance toll cable will transmit a voice at 30,000 kilometers/second compared to open wire velocities of 300,000 kilometers/second. If they are loaded, the speed decreases markedly.

Technically, we speak of “series resistance” per loop mile in cables, for example. This resistance is based upon the cross section of the open wire or cable diameter. Resistance lessens when you increase the area of the wire. Unlike in power, where EHV (Extra High Voltage) transmission lines possess dual, tri- or quad- conductors, telephone pairs are treated somewhat differently. So, can’t you decrease the resistance of the telephone circuit by having two wires (combining their cross sectional size) together? Unfortunately . . . not . . . as the same flowing current is in both wires whereby it proceeds out one wire and reverses on the other. That’s the reason per loop mile, the resistance is twice that of a single conductor.

Carrier. Now you’ve further opened another pot of brew by introducing higher frequencies. Even with cable pairs, circuits conveying signals above 15,000 cycles are not loaded. Special circuit designs require research when a particular pair is selected for service to be “unloaded”. A Local Loop Engineer inspects the MPLRs (Mechanized Pole Line Records) or similar record documentation in determining what pairs need to be eliminated from load coils along the proposed route and turning over a completed work order to have splicers free those pairs from load coils.

Some of you might have heard the expression “H-88” for loading. Let’s briefly touch on this figure of speech. Loading cable pairs at a thousand cycles creates different electrical effects depending upon conductor size. I can remember designing projects in keeping with the H-88 loading preference as facilities were specified served by buried multi-pair copper cable. Just to give you a glance at other types of loading:

H-31

H-44

H-135

H-172

B-88

M-88

B-135, and of course,

H-88

Okay, okay . . . yeah . . . what does the “H,” “B,” and “M” prefix mean? When I worked with Southwestern Bell, this question came up some years ago. Let’s crack open the mystery. A great outside plant transmission engineer I worked with gifted me an old chart. I’ll share it with you, but I’ll make a few points first.

First, when open wire and later, cables were first introduced with loading attended to them, there was a profusion of loading types. When I worked with cable design, H-88 was our preferred loading technique, as most of the facilities on copper paired cable were voice frequency. Our major gauges in suburban Dallas, Ft. Worth, Wichita Falls, Houston areas were 24- and 26-gauge. Since open wire was in its death throwes, and what open wire remained were simple one pair pristine bracket leads with no loading what-so-ever out in the boondocks, the vast majority of these other loading styles simply lapsed from non-use. Hence, H-88 became the “preferred” loading style for most telecom companies, Independent, GTE or Bell.

So here’s the lowdown: The letter stands for per/foot spacing; the number designator reveals the Millihenry (expected) inductance value.

A=700 feet

B=3,000 feet

C=929 feet

D=4,500 feet

E=5,575 feet

F=2,287 feet

H=6,000 feet

J=640 feet

X=680 feet

Y=2,130 feet

So . . . what’s the meaning of the “88”? These numbers are inductance values: hence,

18=18 Millihenrys

22=22 Mh

25=25 Mh

31=31 Mh

44=43 Mh*

50=50 Mh

63=63 Mh

66=66 Mh

88=88 Mh

106=107 Mh*

172=170 Mh*

174=171* Mh

The * designates a margin of application, not erroneous figure.

The larger the coil, usually the longer spacing. Some of these configurations shown above were used with open wire and are “antique” to say the least. Reduced to the most useful and practical designator was H-88. We used it because it possessed lower bandwidth (for voice frequency use), lower propagation velocity, lower loss and higher impedance.

For example: With “LC” for load coil designation, a simplified one line cable design would look like this:

[C. O.] 0′<————–6,000′—————-[LC]——3,000′——[LC]——3,000′—–[LC]—>end

Because gauges in toll cables tend to be larger, such as 19- and sometimes 16-guage conductors, only the H-31, H-44, H-88, H-172 and B-88 are used. What this mysterious nomenclature reveals is that loading is not the end-all solution to attenuation and that there is a practical limit to applying loading to cable. Because as each coil is periodically inserted into the cable length, the series resistance and inductance is increased along the conductors. Once you have increased the resistance to such a degree with excessive loading, then you’ve exceeded the whole purpose of these devices. My understanding when designing cable loading was that 18,000 ft. was the most extensive allowable length. This was because transmission gain maximums exceeded efficient operation of the cable pairs.

How were loading coils spaced? This depended upon the gauge of the cable and the length from one end to the other. If we used H-88 loading, for example, on exchange (near a suburban C.O.) and it was 24-gauge, loading coil spacing from the C. O. to the first coil would be 6,000 feet. Cutoff frequency would be 3,700 cps. Attenuation would expected to be only be 1.13 decibels per mile. For 22-gauge, 6,000 feet spacing would remain the same, however, cutoff frequency would be less: 3,500 cps and .79 decibels per mile losses incurred. Telephone people refer to the margin of installation as “hand-grenade accuracy.” Meaning that a buffer of installation spacing should have been (in the early years) kept below 2% deviation. Later, loading coils became much more efficient and 5% was allowed. Open wire load points were very crucially sited; cable much less so, and had greater margin.

One further note. In the early days of cable, from its introduction to around the 1940s, cables were not necessarily, as today, packed with copper pairs of the same gauge, i.e. where a ANTW-200 (buried) or BKTS-200 (strand-supporting aerial) cable were all 26-gauge pairs. If you note the A&B Cable example in the “Obituaries of Open Wire” within this website, the cross-section reveals several different gauges. This is no longer done and fell out of favor by the 1940s. I worked on only a few cables which reflected this characteristic.

And . . . here’s the most unappreciated fact of all, regarding the loading of cable pairs vs. open wire. Besides eliminating the “cut-off effect” (in the old days it was referred to as “Lumpiness” of coil loading in open wire) and where “unloading” allowed higher transmission velocity on aerial wire, greater long haul stability in with open wire was achieved. This resulted because, in general, open wire had lower characteristic impedance and further freedom from speech distortion. One attendent issue with loading was when you “load” or re-generate strength of a pair’s signal, you also re-generate the static–interference noise as well. This is where repeaters, for digital systems, were introduced with considerable promise in the years to follow. Echo effects and velocity distortion were troublesome in the early years, too. With improvements in the newer materials used for loading coils, such as Permalloy, introduced by Bell Laboratories in the mid-1920s, the full potential of extending telecom across the continent and lowering costs was fully realized–for cables.

Another point: in the early development of loading systems, engineers debated, “At what range of frequency should be transmitted?” This fundamental question was considered and a “standard” cutoff frequency of 2.3 kc was adopted.

Internal Appearance of a Loading Coil

Let’s look at how these little buggers are constructed. Our lesson today will also introduce some other features which make them quite useful devices for signal quality as well as improving efficiency of signal quantity (as in allowing as many cable pairs possible to be practically packed within a limited circumference insulated sheath).

For an efficient loading coil properties, the less winding resistance the better. A loading coil must have a coil with very low loss and a perfect equilibrium must be created by inductance. To clarify this, consider a loading coil divided in two. Since one wound energized wire is the “speaking circuit”, opposing it on the other side of the wound donut is a similarly wound circuit. Both have an equal number (ratio) of turns. Around the core traveled a magnetic field created by two windings. When current reversal occurred, the circuit experienced “inertia” or inductance to the circuit. The reason for the toroid shape makes magnetizing of the coil easily with as few losses as possible.

By the way, each “pot” was not only installed with coils, but surrounded and bathed in insulating mineral oil, just as other electric power equipment saw similar application. These were hermetically sealed and no moisture was allowed to enter. There was a gasket around the top case and several bolts held the cover on the larger units. Smaller pole-mounted units were encased in lead with no option to open or inspect the interior coils.

Each “pot” contained a spindle upon which were piled these many individual coils. Occasionally, loading coils were placed in cable splices. I might also add, long spans of C-Rural Wire had installations of loading. Let me dig up one from the collection we’ll photograph it here for you. C-Rural Wire largely replaced open wire bracket leads.

C-Rural Wire Loading

This is a front view (rubber cover removed) of a Western Electric model 178A1 Coil Case Unit. These were very common in the 1960s when C-Wire began to take the place of open wire bracket leads. Note the strap for fastening the unit to a pole with two top and bottom lag screws. The oval holes on each side of the disk are for the C-Wire to be pulled through from the rear, crossed over and then spliced opposite the wire direction entrance to avoid wire strain. Binding posts secured the C-wire pairs (tip and ring) when the wire stripped back and tightened.

While we’re on the topic of loading, it could be accomplished on the most minimal of circuits, not just multi-pair cables. Since C-Wire (which is a plastic jacketed, very high strength drop-type paired conductor, similar to regular drop wire, but tough enough for long spans) is used to replace many open wire bracket leads, we’ll discuss how it was loaded. GTE, the Independents and transportation companies all had a similar type “wire” and applied it to similar situations where open wire was removed and replaced by it. If the C-Rural Wire followed a particularly long route, the application of a single pair loading coil was specified by an outside plant engineer. Bell used the Western Electric 178A1 type loading coil. It was extensively applied to C-Rural Wire, as I believe Reliable had something very similar to it for the Independent companies’ use.

Side view of same loading coil for C-Wire. The diameter of the unit was about three and one fourth inches. The the whole device top to bottom was five and one half inches. Cover was made of flexible neoprene rubber and was just squeezed on the solid core. No screws held it in place.

The little hand-held sized, resin-filled, loading coil for one pair was took on the appearance of a large biscuit. It was about six inches in diameter and had a rubber cover, to be removed to access connections inside. A mounting bracket formed the rear of the device support. Two mounting screws, above and below, the device single metal bracket would allow it to be applied to a pole side, directly below the drive hook where the C-Rural Wire was dead-ended on “Pre-Formed C-Wire ends.” The loops from both of the incoming and outgoing pair were cut and then threaded through the entrance holes for the wire. This allowed for “drip loops” on each side of the coil entrances.

Impressed upon the rubber cover was specifying nomenclature for ready identification and the proper size selected for specific C-Wire placement.

This is a rear view of same unit. Note the whole unit was resin filled and had no access to the plastic encased metallic core and conductors.

What made this little load coil unique was “built-in” or integral protection to meet any surge currents from lightning or power contacts of the C-Rural Wire spans. Two protector units by-passed the errant currents around the coil. They were not ground-wire bonded to pole.

These were seen quite often in the early days, but it takes some searching to locate C-Rural Wire with loading today. It’s out there where you might have seen former bracket lead open wire. If you spot it, the miniature black Oreo-shaped loading coils quickly appear to the eye where particularly long span services cross to farmsteads. I might also add: open wire lines often supported C-Rural Wire on crossarms. It was quite common to see the C-Wire Support or “D-Wire Bracket” with pre-formed spirals, formed over the crossarm and the C-Rural Wire suspended directly under the ten-pin crossarm–typically between the 3rd and 4th or opposing, the 7th and 8th pin if two or more C-Wires are used. No bolts, lags or preformed tie materials were used, simply the “C” shaped high strength steel unit.

C-Wire was a quick and dirty solution to avoiding placing another arm or bracket lead with minimal clearance to ground or to another arm beneath the top arm.

Squirrels never touched open wire in my experience. It was greatly different when C-Wire was installed to replace it. In Texas, we found squirrels LOVED chewing on it! More outages were caused by this problem than open wire ever presented us with! The little incisors of these rodents found C-Wire insulated jackets a choice selection when their ever-growing teeth needed to be worn down. Another reason why open wire was superior in many cases to this alternative. A little chewing and . . . pop! . . . you had a shorted pair.

What About Loading Telegraph Circuits?

What a great question! Let’s go back to when the telephone and telegraph industry was maturing in the 1920s. Telephone companies, as well as railroads who leased much of their open wire to telegraph companies such as Overland, Postal and Western Union, the virtues of compositing were clearly identified. Many of these circuits in the early days were loaded and by simultaneous transmission of both telegraph and telephone on the same wires made much sense economically. However, within a few years of implementing this process, a unique electrical effect was identified: “flutter.”

Flutter was produced by the cores of the loading coils applied to the circuits. What happened in the course of combining telegraph and telephone signals was a current “modulation” effect. This was first encountered around 1921 and the race was on to eliminate this problem. Since the problem wasn’t originating with the physical transmission line, but in the coil itself, clearly the design of the coil had its faults.

When you examine a loading coil, it has a “core” made of iron. When experiments were conducted with high and low permeability iron, the “low” type demonstrated better operational efficiency. This, in turn, allowed loading coils of lower permeability to be installed on major toll circuits where the conductor gauges were considerably larger. The experience of using low permeability cores was a major improvement in cable and eliminated from open wire use. A few years later, by the mid-1920s, air-gap loading coils were adopted as a further advancement in their design and “flutter” was substantially reduced with superimposed telegraph and telephone systems on nearly all long distance telephone routes.

Powdered iron was used in the early loading coils and with long repeatered lines, worked advantageously. This electrolytic-deposited iron, ground to a talcum powder density was insulated by an industrial process before compression into its characteristic ring shape. This solid shape was the result of high pressure compression, but having little tensile strength. Because solid iron cores were not used, these powdered cores possessed microscopic small air holes throughout. While not mechanically strong, this characteristic allowed them to be very magnetically stable, thus eliminating magnetic leakage effects. Being very stable, the inductance values were kept constant, even when external inductive effects of nearby A.C. power circuits, thunderstorm effects and minor short circuits, passed closely to the circuits.

This photo, from 1903, illustrates the induction problem to nearby electric power and telecom/signal circuits.

It was found later, these stable cores could withstand a considerable amount of D. C. current temporarily.

The actual production of these small core assemblies was conducted very uniquely. The iron particles were separated by cathode plates suspended in tanks, the purest iron removed, smashed into fine particles an inch square and ground up. Each iron particle received an oxide coating and some shellac. After one hundred tons of pressure, these rings emerged from pressing where 35,000,000,000 particles were contained in only seven (7!) small rings! This greatly reduced magnetic instability and impedance was very uniform through this compaction.

The rings were then assembled one upon the other meeting the dimensions relative to their electrical application. Typically, a paper covering of kraft or similar material was applied for protection between coil conductors. In a large assembly, tightly confined within, were hundreds of these units, all connected individually to their pairs within a copper cable connection. Needless to say, these very heavy units took up much space and were extremely heavy. You may see them on poles or H-fixtures, or if you are lucky enough to visit a vault or manhole, deep on the floor of the hole.

Open Wire is Freed From Loading

Concern over circuit loading posed a problematic situation. M. I. Pupin, a recognized Professor of engineering at Columbia University, in early 1900s, invented an early style of coil loading. What he, and Dr. G. A. Campbell of AT&T’s research arm accomplished, was if inductance coils were placed uniformly along a lead, these “lumped inductance” would render electrical qualities along its length largely uniform. Here’s where the length of electrical waves and loading coil placement design coincided.

One of the big problems with the coils was efficiency. By 1904, the early cores were designed and built with iron cores made of spun iron wire. A single core was wound with about ten miles of conductor it for a single core! Each wire was lacquer coated for insulation. This prevented eddy current losses. A copper winding was then run on each half of the doughnut with leads extending out to connect with the EAST – WEST pairs.

Others, such as Thomas Shaw, further perfected this design technique around 1900. When the issue of phantom loading came up and fear that loading might make its use challenging, first installations between Boston and Neponset, on multi-pair copper cable in 1910, presented no problems.

Between 1904 and 1916,many new advances in constructing more efficient coils and cores overcame previous less efficient designs. In 1916, the use of fine powdered iron compressed into rings and then each inserted above each other was the conventional process of manufacture. Then came World War I. Interestingly enough, the war in Europe had blockaded the diamonds imported for use in the drilling dies. These dies allowed fine wire to be drawn drawn through the iron cores. The problem became so serious that future production of the previously manufactured type appeared impossible.

By 1926, designers of toll open wire were backing down on further installations to load them. Bell, and other major carriers, eliminated it from new aerial wire facilities being built. In those days, the major open wire toll conductor gauges were primarily 165 mil and 104 mil high strength copper. The repeater was making its inaugural appearance by 1915 and open wire carrier was being slowly introduced for the first time. By 1922, some advanced work on carrier was underway. With the higher frequencies of carrier systems, loading stood in the way of effective carrier transmission over open wire. Another roadblock to applying it further to toll open wire.

Early information on phantom circuits exposed to repeaters and their effects, 1927.

Repeaters’ development offered the first electronics dramatically exceeding lengths of conventionally constructed open wire toll wire. Repeaters were also introduced into cable circuits with amazing success. With their first cable installations, cable lengths were pretty short, contained large gauge conductor pairs and grounded telegraph was superimposed upon the telephone pairs. Loading coils were then ample in affecting efficient use of these multiple use lines. And, let me suggest, even with the advent of the first electronic repeaters, there was no fundamental changes to engineering existing loading coils, except to be more precise as to intermediate physical locations when installed on these early short-haul cable leads.

Distortion effects, typically caused by grounded telegraph circuits, were slowly eliminated when low permeability type cores were used. Further advances in air-gap units, also made their installation throughout the United States and Canada opportune.

One other factor influenced open wire’s freedom from loading: series inductance. When open wire lines were constructed, depending upon their transmission purpose, early pair spacing was uniform nearly everywhere based on the 1885 design. Later, with the advancement of carrier, efficiencies were found where varying this distance was necessary for proper operation. Original open wire lines, 12-inch between pairs and 16-inches between pole pairs, was a given. Later, requirements for higher efficiencies dictated the use of 8- and 6-inch spacing and elimination of the pole pairs and phantom pairs. Cable was quite different. Crammed into the sheath were pairs which typically were twice the insulation thickness. So per loop mile, the inductance variation required engineering for operation with and without carrier.

Permalloy Loading Coils

The efficiency created by the use of loading coils was well established, but as more cable was introduced into long distance outside plant in the early 1900s, applied also to inter-office trunking from open wire toll, pioneering work began to perfect the loading coil further.

On the Transcontinental U. S. open wire lead, the loading coil cases for these strands across the Western United States, were substantial in weight and size. Pacific Telephone & Telegraph regularly installed pots containing three loading coils: two for side circuits and one for the phantom of all four wires.

But by 1926, the size of the coil was substantially reduced, and economies were gained by smaller case sizes where attached to cable poles, manholes and H-fixtures. This came about because of the innovative “Permalloy” introduction by Bell Laboratories.

Essentially, “Permalloy,” is a patented AT&T trade name for a specialty bi-metallic material combining 80% nickel and 20% iron compounds. A guy at Bell Labs by the name of G. W. Elmen, discovered it. He decided to try a practical application and found use when loading of the transoceanic telegraph lines. Here the permeability factor–which in Permalloy had highly developed magnetic qualities–was concentrically wound around the telegraph wire in the submarine cable. When installed between Atlantic coasts and heated up, what telegraphers immediately discovered as signaling speed rose dramatically. More telegraphic traffic raced over such a loaded condition, making for many more communications possible than the previously laid conventional submarine cables.

Engineers deduced by using Permalloy in conventional terrestrial cable routes, similarly a parallel advantage might also result. The promise of the loading material was obvious. However, clearly, the submarine cable process had many changes in store before it could be applied to aerial cable crossing land. What caused such positive notice was the material’s low losses–particularly the form of “hysteresis” loss. What hysteresis means is when magnetization results within the core, there is a lag or slowing, relative to the magnetizing force.

Soon, by the mid-1920s, the practical device whereby the Permalloy was used, was achieved and industrially produced for application to aerial cable lines of significant length. And as many open wire toll circuits were being converted to cable, its application to the loading of open wire simply diminished . . . and faded.

“Frogging” Circuits

Let’s leap frog to the relatively humorous–but practical topic of creating electrical equivalency in open wire or cable wires by linemen, installers and splicers. I’ve heard this term from old-time open wire linemen, installers, splicers and railroad signalmen often. Having asked what this odd expression meant, I can assure you, as old as the hills it indeed is, it survives today as a common day phrase! What a splicer is doing with a cable pair by “frogging” can be, for example, at the end repeater sections, when the distance between repeaters exceeds a desired half-section. Perhaps, in this situation, 19-guage circuits might be brought in over 16-gauge circuits in this last repeater section. In open wire, a 12-guage might be “frogged” with 8-gauge in cases where a long repeater section may be encountered and the use of 12-gauge won’t provide the equivalent necessary.

Below is an interesting example of “Loading” in early radio. This page is from a 1926 Ohio Brass Company catalogue.

Travelling Waves on Transmission Lines: Inductive Loading

By Tom Hagen

Introduction

This article is a continuation of the second article on transmission lines, specifically covering issues affecting transmission of frequencies on open wire telephone lines.

Information I wish to acquaint you with through this article.:

More results from Traveling Wave Transmission Modelling:

Traveling waves on transmission lines

Phase distortion problems on transmission lines

Lossless lines; distortionless lines

Some practical examples:

Michael Pupin and others

Loading coils on telephone lines

Distributed inductance to improve telegraph cable speed

Background

In previous articles, I’ve written about how the development of long undersea telegraph lines drove the need to deal with the effects which degrade signal propagation on long lines (See chapter on “Telegraph on Open Wire Lines”. The development of electromagnetic field theory by the “Maxwellians” was instrumental in continuing this work in the telephone technological field. Audio alternating frequencies are passed by telephone lines to represent speech in the 300-3,000 Hz frequency range. Electromagnetic field theory illustrates these A.C. signals are actually electromagnetic waves travelling in the space between the wires, and are not represented as voltages and currents flowing in the wires.

One result of this new theory was higher frequencies travel down the phone lines faster than at lower frequencies. This effect is called “phase delay” or “phase distortion.” On longer lines, this causes distortion of the voice signal because the time relationships of the original signal are lost, thus causing phase distortion. Remedies in the form of inductive loading coils are applied to address this condition. Loading coils are placed at regular intervals on phone lines to reduce both phase distortion and attenuation of higher frequencies in the voice range. Another desirable effect of loading coils is reducing the attenuation, or reduction, of the signal strength over the length of the long open wire pair. The theory behind this development was first elucidated by Oliver Heaviside. Michael Pupin patented the loading coil.

Travelling Waves on Transmission Lines

A single frequency sine wave signal, say of 1kHz frequency, travels down an open wire pair transmission line and can be represented as in the diagram below:

The magnetic field from the current flowing in the transmission line wires is at all points at right angles to the electric field lines from the opposite charges on the line pair. Under these conditions, the math explaining the field conditions on the transmission line show energy is transmitted down the line in the form of traveling waves. These waves travel at near the speed of light, or around 186,000 miles per second. Note that free electrons in the wires simply provide the conditions for the traveling wave to exist. The electrons themselves just jitter back and forth on the line as the waves pass by. I would like to compare this to striking a line of billiard balls. The impulse shoots through the line of balls, but the balls themselves barely move due to the impulse.

Without going into the fairly involved math (differential equations, real, complex, and imaginary numbers and so on), I’ll just present the results. There are plenty of sources online and within books on transmission line theory, if you wish to delve further into transmission line mathematics.

But first, we need to examine a circuit model of a transmission line. The simplest transmission line is a pair of parallel wires. Currents flow in opposite directions on each wire and there is a potential difference, or voltage, between these conductors.

The circuit below represents a tiny chunk of this transmission line. There is a series inductance in each wire making a magnetic field around the wire (magnetic fields form around current-carrying wires), capacitance between the wires (electric fields form between the wires when they have opposing voltage potentials applied to them). Then, there is series resistance of the wires themselves, represented by the series resistor in the diagram. And, finally there is leakage current between the wires represented by the resistor connected across the transmission line pair. The constants are represented by the symbols L, C, R and G, respectively. L is inductance, a unit of Henry, C is capacitance in Farad, R is resistance in Ohm, and G is conductance in Siemen. The “dx” element represents infinitesimal distance, as the length of the transmission line element is very, very small. The entire length of the line is composed of an infinite number of these infinitely tiny chunks strung together in series. The four parameters are evenly distributed along the length of the line and are specified as “Henry/meter,” “Ohm/meter,” “Farad/meter” and “Siemen/meter.” The behavior of traveling waves on this type line is dictated by the value of these distributed parameters.

One of the interesting results of this theory is if the line is “lossy,” (or has values of R & G greater than zero), then higher frequencies travel faster on the line than lower frequencies. This causes phase distortion. Another effect of the lossy line is higher frequencies are attenuated more than the lower frequencies. Recall: attenuation is signal loss that occurs along the length of the line.

Inductive Loading on Transmission Lines

The mathematics proving these assertions I’ve previously mentioned, was developed from the simple distributed parameter model and is not trivial (See the Wikipedia article on Transmission Lines to flavor the mathematical details). Oliver Heaviside and the Maxwellians, in addition to developing the transmission line mathematics, arrived at a solution for the attenuation and phase distortion problems by proposing what is called the “Heaviside Condition for a ‘lossless line'”.

The equations show that if

the velocity and attenuation are no longer functions of frequency, which definitely is the case for a lossy line.

Typically, in the real world,

for a lossy line, so that if L is somehow increased along a telephone line, the R/L term is reduced in value and can be made to be equal to the G/C term.

Another benefit that drops out of this technique is attenuation is made to be constant across the frequency range of the line.

Now, as we have the concept of line attenuation and phase distortion clarified, let’s talk about remedying this situation. Michael Pupin of Columbia University patented evenly distributed loading coils and made a fortune out of it. He published a significant paper in 1900 detailing the use of loading coils and also patented these coils in 1899.

Michael Pupin (1858-1935)

He became a wealthy man when AT&T bought out his loading coil patent in order to avoid patent interference with Bell’s own loading coil development work.

How are inductive loading coils used on telephone lines? In our figure below, the coils are made up of toroidal ferromagnetic material and both wires of the pair are wrapped around the cores to provide series inductance at regular intervals. Coil spacing on long phone lines may be on the order of 6,000 feet.

See the many fine references and pictures of real loading coils in other sections of the Song website.

A problem with using loading coils is they make the phone line behave like a low pass filter. When the coil values and coil spacing are optimized to minimize distortion and attenuation in the voice frequency range (approximately 300-3,000 Hz), the frequencies above 3 kHz are sharply attenuated and the line cannot pass frequencies above 3kHz. This would not normally present a problem, but when phone companies began providing digital service via digital subscriber line (DSL), the lines proved to be inadequate to pass the higher frequencies required. DSL can use frequencies as high as 4 mHz, and loading coils must be removed from the lines in order for DSL to function.

Another service, very high bit rate digital subscriber line (VDSL), requires up to 12 mHz bandwidth for a maximum of 52 Mbit/s data rate. Note: the highest VDSL speeds can only be achieved out to about 1,000 feet from the phone line pedestal/terminal. This limit is set by line loss which at the higher frequencies is caused mainly by leakage conductance and insulation dielectric loss between the two conductors of the phone line pair.

As an aside, undersea telegraph cables used continuous inductive loading to overcome the same distortion effects of telephone lines. Without loading, cable speeds were limited to perhaps 400-500 letters per minute.

The inductive loading was done with a material called mu-metal, having very high magnetic permeability. This property allows mu-metal to absorb and retain magnetic fields much more readily than air or other non-magnetic material surrounding the conductor which it is wound about. With the mu-metal loading wire wound around the center conductor, the series inductance is significantly increased and the Heaviside condition of:

is met. Since the mu-metal winding provides continuous inductive loading, the telegraph cable does not act as a low pass filter. Inductive loading of telephone lines in this manner is expensive and normally not done. Also: having a cutoff frequency above the highest voice frequencies was not a problem until the advent of phone line multiplexing, frequencies above 3kHz were not required on telephone circuits.

With inductive loading, speeds of 1,900 letters per minute became possible, or about four times the speed of unloaded cables. Note that 1,900 letters per minute corresponds to about 2,000 bits per second. By comparison, today’s undersea fiber optic cables transfer upwards of 15 trillion bits per second on a twelve-pair cable.

See also Tom Hagen’s contribution at:

the-electric-orphanage.com/telegraphy-on-open-wire/

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We are seeking interesting stories of those who worked with this amazing technology. Do you have photos of sleet-damaged structures, wide canyon or river crossing special structures, early construction or line wrecking photos? Did you work in the past for an independent telco, a Bell company, an REA-financed cooperative association or are employeed today in the telecommunications field?

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How did open wire as a pioneering effort improve later technologies? How did it lend a hand by making possible later developments in our present progressive and efficient state-of-the art communications systems of today?

My Memories of

Open Wire

By Fred M. Cain

Archival photos by D. G. Schema

My personal thanks to Fred M. Cain, who allowed permission to reprint his original article which appeared in the June 2006 TCI Singing Wires periodical, so visitors to our Song of the Open Wire guests might share his well-written narrative. I asked him earlier about how he came to share this information.

"How did I come to write the article? Good question. I'm not sure I remember exactly anymore, but at one time, I fantasized about doing a book on the subject. But in the end I scaled that down to an article. I had a terrible time finding good photographs of open wire lines as I remember. The AT&T museum in Denver told me they had lots of pix but I'd have to travel to Denver to see them. That simply was not an option for me at the time. So, I tried to make due on what little I had. I hope someone writes a book someday. It seems like such a shame that a unique, although somewhat obscure piece of Americana should disappear and become forgotten. My Route 66 Project is actually not new. I had the website launched in 2003." Mr. Cain is associated with the "U. S. Route 66 Recommissioning Initiative [http://www.bringbackroute66.com/home/html].

Part I: Personal Perspectives

What is it about open-wire telephone lines that I find so thoroughly fascinating? That's a good question I have sometimes asked myself. Open-wire telephone and telegraph lines were an important part of North America's telecom transmission system for almost 100 years. Open-wire telephone lines were also a once common, familiar sight in rural areas which has all but disappeared today. Consideration of these facts helped lead me to the opinion that open-wire telephone lines are worthy of study.

I can trace my interest in telephone lines back to my earliest childhood. Even as a small child, I seemed to have an early fascination with all things mechanical and things to do with electricity. Having such an interest led me to observe open-wire telephone lines didn't look like the other more common utility lines found in our suburban residential neighborhood; they were distinctly different. By the time I had come into the world, open-wire communication lines were found largely in the country. You didn't see them much in town.

Our family also traveled quite a bit, crossing the United States three times by the time I was thirteen. In the pre-Interstate Highway days, rural, multi-arm open-wire telephone lines could often be seen running alongside the older two-lane highways of that era. Sometimes there would even be an open-wire line pole planted right in the front yard of a roadside motel where we'd spent the night. Thus, I guess, my young mind came to associate open-wire lines with the joy and thrill of traveling, going someplace new and exciting and doing something different.

As I grew older, I began to notice that open-wire telephone lines were becoming increasingly uncommon. As a life-long advocate for the underdog, this only sharpened my interest in them. I seem to have many memories and images stored in my head. I have attempted to share some of my memories here with words and a few pictures I've been fortunate enough to find. I then tried to draw some conclusions on the plight of open wire.

I was born in 1952 on Long Island, New York, but before I was a year old we relocated to what was then a still largely rural part of Fairfield County, Connecticut. During those early years, I would often ride along with Mom to the store or on other errands. I can remember one day she took me for a ride and something along the road leading from our housing development caught my eye I hadn't noticed before. Something, you might say, that even struck me as rather beautiful in its own special, mundane way.

I saw a bunch of brand new, shiny, copper-colored wires held by sparkling glass objects glistening in the bright sunshine. Wow! There must have been twenty of them! I thought they were nice enough that I watched for them the next time Mom took me down that road. But they weren't there. It was like they hadn't been there until the day I first saw them but the next time we drove along that road--GONE! Did something like that really happen . . . or did my childhood memory play some kind of trick on me? Perhaps I had somehow confused two different locations or time periods.

A great source of wholesome, family entertainment during those years was the "ride in the country" in the family car on warm summer evenings. It stayed light late and didn't cost much as gas was probably around seventeen cents a gallon. Riding around in the country, I began to notice more wires where we lived. Along one rural road just off U. S. Route 7 in Wilton, CT, not far from where my older brother played little league baseball, I can remember seeing a large, multi-arm line possessing at least four crossarms and could well have had five or six. It started near Route 7 and ran westward along a rural byway back into the hills. I can remember being amazed and intrigued by all those wires and mystified as to where they went and what they did.

In the fall of 1958, we left Connecticut and moved out west to Tucson, Arizona. Bored and restless from being cooped up in the car for a week, I tried to amuse myself as best I could by looking at the roadside wires. I can remember driving somewhere in the South along a two-line highway that came to a rural stop sign. We stopped and turned right following the route we were on. Perhaps it was was U. S. Route 11? One amazing pole line followed this road. This was the first line I can remember seeing with mid-span transposition brackets suspended in the wires, but I had no idea what they were. I tried to ask Dad but he was too busy driving to look up and see them.

Arizona was a different world from New England, yet open-wire telephone lines were everywhere. There was a wide range from large, multi-arm toll lines down to lines that carried only a single pair of wires on short spindly poles back through the wilderness to reach some remote minding or ranching community. In fact, I would go so far to say that nearly everyone who was living well outside the city limits was either on an open-wire line or connected to one at some point.

During the four years we lived in Tucson, we made annual summer trips to California since much of Mom's family lived there. California had gobs of open-wire, even more so than Arizona since so much of California had a higher rural population than Arizona. There were many places in Southern California as well as the Central Valley that had much in common with the Midwest--except with no snow or ice. This circumstance favored the longevity of open wire there.

I can remember sitting on my grandfather's porch in the evening in San Diego listening to him tell his life's stories. As the sun sank to a certain low level, it cast long shadows and I could make out the silhouette of a distant two-arm line at the top of a hill on the opposite side of the valley. To this day, I can close my eyes and envision this scene.

In 1962, after another swinging through California, we moved back to New York, coast-to-coast on U. S. 40 this time. Back on Long Island, we resumed our evening rides in the summer. Occasionally, we'd drive up to our old stomping grounds in Connecticut. It was during this time that I first began to notice that the quaint, multi-arm lines were disappearing from the countryside.

We went back to my brother's old ball diamond in North Wilton and even drove down that lane off U. S. 7. The multi-arm line was gone! I can remember asking, "Dad, what happened to the telephone lines that used to run along this road?"

He replied, "They're still here," as he pointed up at several black telephone cables. "No, Dad, not those. I mean those other wires with all those arms and glass beads."

"'Beads?' I guess I'm not sure what you mean?" He couldn't recall the wires and probably hadn't noticed them in the first place. Later I showed Dad a photograph in the Encyclopedia Britannica [try looking up "telegraph" in the 1952 edition--you'll find it].

"See Dad, this is what I'm talking about--see the glass beads?" "Oh, yes," said Dad, "those are insulators." About all he could tell me about such wires was that they were old fashioned and that a as a child he once found a "green glass insulator" in his front yard in Port Huron that he treasured dearly.

Other than what sketchy facts I was able to glean from the encyclopedia, the only available method of obtaining information was by simply asking people. We had what I can only describe as a "grown-up kid" living in the house next to us on Long Island. He was a great deal older than me, probably in his late teens or early twenties but he still acted like a kid. In the lingo of later years, he could best be described as "rowdy," although the term was unknown to me at the time.

I will call him Larry Bletcher [not his real name]. Larry's family had a fireplace and a huge outdoor woodpile to go with it. After school one of my close buddies and I would often go over there and help Larry split wood. Larry would derive immense enjoyment out of entertaining us with his jokes and words of wisdom on the "real ways of women." To a pair of 13-yearolds, Larry was "beyond cool." To someone closer to his own age, though, he would no doubt be considered a bit of a jerk.

At any rate, during one wood chopping session, I began talking about my interest in telephone lines. Larry got a strange twinkle in his eyes and told me something like, "Freddy, I have to go up to our summer home in Vermont next week to fetch a new load of wood. I'm gonna' bring you back a little present."

"Oh yeah? Like what?" I responded. "You'll just have to wait and see. Remember what I told you, I will bring you back something."

A couple of weeks later, after I'd forgotten all about it, my school buddy and I were back over there chopping wood again when Larry approached me. "Here, Freddy, these are for you."

He handed me two beautiful, emerald green insulators. One had a round head and a good fat, tapered skirt on it with only one narrow, shallow wire groove. The other was very narrow with a pair of "lips" near the top to hold the wire.

I was absolutely ecstatic and yelled out, "Larry! Where in the world did you find these?" "In Vermont, near our summer home," was his brief response. I pressed on, "But where and how did you get them?" "I just got a adder and climbed a pole," he said matter-of-fact. I pushed further, "Did they still have wires on them? "Of course," he said in the same tone once again. "Then how did you manage to get them?" He simply responded, "Snip, snip."

My friend who was standing nearby listening to this exchange burst out into uncontrollable laughter. Did he really? Did Larry Bletcher really do that? After all these years, I have no answer for that. You had to know Larry. He might have just been having fun with me. But he could have just as easily been entirely serious as well. Who knows?

During this time, I made many forays on my bicycle from our house on Long Island in search of open-wire, sometimes riding for miles and going places I really wasn't supposed to go. I found some along the railroad tracks in a few places, but that's all. No active, public telephone lines.

My older brother Robin was attending the University of Connecticut during this period. I went up to visit him for a week one time and he gave me a tour of much of eastern Connecticut and west central Mass. I was fortunate enough to see a few rural open-wire leads still in service there.

My Dad had a friend in our church whose name escapes me, so we'll just call him "Mr. Hearst." Dad and I had lunch with him one day. During the lunch conversation, he mentioned that he worked for New York Telephone. I proceeded to barrage him with a slew of questions. He old me that until very recently, the Company had a lot of open wire out on the eastern portions of the Island but he thought that it had all been taken down. "But, if you look hard enough, you might find a pair or two here and there that we missed," I can remember him saying.

I asked him why they took it all down? He basically blamed the weather. "It works great until you get an ice storm or a snow storm with wet, heavy, sticky snow. First it sags under the weight . . . and then--boom! It's down!"

One day I was outside playing or something when Dad came home and yelled at me, "Freddy! Come over here, I've got something for you!" I walked over to the car and he proceeded to hand me a rather large grocery bag.

"Watch out! Be sure you put your hand on the bottom. It's heavy. Mr. Hearst asked me to give these to you." Heavy indeed! It's all I could do to manhandle it to the ground without dropping it. When I opened the bag and peered inside, my eyes just about popped out of my head! It was filled with clear glass insulators. They were all the same with a flat top and straight sides with two wire grooves if I remember right. I used them to build a very crude, primitive, but entirely functional telephone line on our property. Later, I asked Hearst why they had two grooves but just gave me a blank stare. "I guess because that's the way they were made." Later I realized they were in fact used on a particular type of two-insulator transposition bracket.

During the summer of 1965, I learned we would be returning to Arizona once again. The trip back took us down much of Old U. S. Route 66, an experience that left me with many fond memories and helped galvanize a life-long interest in our most historic route designation. As had been the case on a lot of other family trips we took together, I also saw a good number of open-wire lines, many of them in their declining days.

Life in Arizona in the 1960's was great for a budding open-wire enthusiast. Not only were there still gobs of it in use but it also remained a very active part of Arizona's expanding telephone system at the time.

One day, I decided to go on an "open-wire search" with my bicycle--probably one of the very few times in my life that I had the good sense to bring my trusty "Brownie" camera along. I shot a number of open-wire lines that I found in different older housing developments. A few of them were right in people's backyards. Presumably these were all once rural areas where the city had simply grown up around them but the wires remained.

I shot one neat looking one-arm line up in the vicinity of Swan Road and Grant, although I cannot recall its exact location. It wasn't really a very long line, but it did have 16 pins on it! After I left the scene, I passed a telephone man just around the corner who had stopped his van and was doing something in a cable junction box. I unsuspectingly approached him and tried to peer over his shoulder to see what he was doing. To my mind it looked as if he was struggling with a million nerve endings.

He turned to me and seeing my camera exclaimed, "Hey kid! Whose picture ya' gonna' take?" "Well, actually, I brought it to take a picture of the telephone wires." "Oh yeah? What wires you talkin' about?" "Right back there. There's some really neat-lookin' open wires, you know the ones I mean?" He just snarled back at me, "Oh, yeah, I know. Those are comin' outta there one of those days."

I was a bit taken back by what I perceived as his negative attitude. Why? How dare him say such a thing about those beautiful . . . some thoughts passed through my head. I wanted to ask him what could be done to save them. But then, I realized I couldn't provide a truly compelling reason to save them right off the top of my head other than the fact that I just wanted them to . . . remain. I thanked him for his time and bid him good day.

At this time in the '60's, there were also several toll lines that connected Tucson to the neighboring cities and towns. Of particular fascination to me was what I liked to call the "monster toll." This was a five-arm lead that ran along the Southern Pacific Railroad from Tucson west all the way to Riverside, California and eastward through the desert on its own right-of-way to El Paso, Texas. One segment of the line ran right through town alongside busy 22nd Street--a major Tucson thoroughfare--evoking visions of a scene straight out of the 1890s.

Our second stay in Tucson didn't last very long. Dad was offered a much more attractive engineering position at another firm so in the fall of 1967, we moved to Scottsdale in the Phoenix area.

The Phoenix area back in 1967 was much larger than Tucson even at that time. However, like Tucson, there were still some open-wire lines to be found in older residential areas. There were also open-wire lines, too numerous to mention, out in the Carefree and Cave Creek areas as well as over by Lake Pleasant. Many of them were still new in 1967. Most, however, were only five pairs or less. These areas were still sparsely settled at that time with only a smattering of ranch homes here and there. Many of these subscribers were hooked up to the phone system with open-wire.

Like Tucson, Phoenix also had several toll lines that connected to nearby cities and towns. Of particular interest to me was a fascinating line that connected to the "monster toll line" in at what was at the time only the tiny little town of Maricopa south of Tempe. It ran northward along the Maricopa Road ending on the south side of Tempe where it entered a lead-sheathed cable. I distinctly remember the line carrying four arms during its last years in operation.

On at least one occasion, we drove to Casa Grande "the back way" by going down the Maricoipa Road. The line ran right alongside the very edge of the road. It was quite a spectacle, all those wires and all that glass sparkling in the desert sun. You almost felt like you were driving right in the wires!

After graduating from high school, I headed back down to Tucson to attend the University of Arizona in the early 1970s. I explored on my sparer time. On one trip, a friend from my dorm, Barry Roberts and I, started out on our bicycles and rode east out of town along the Vail Road. This area was still largely undeveloped at that time. Somewhere along there we came to a spot where the "moster toll line" crossed the road on its own right-ow-way headed toard Vail and Benson. By this time, it had been cut from five arms to four.

"Hey, look at this!" I exclaimed to Barry. Barry was no open-wire enthusiast but none the less he couldn't help be impressed by all those wires and all that glass. He had his camera with him and took several pictures of it for me. He promised to make certain that I got the pictures. But as time passed, I lost touch with Barry and never did get the photos. That just seems to be the way my luck has gone.

My college career was difficult for me. I dropped out of school and went back several times. After several false starts, I finally graduated from Arizona State University in Tempe with a Bachelor's Degree in music therapy in 1980. I then returned to the northeastern United States. By this time, Mom and Dad had relocated to the San Francisco Bay area.

In the summer of 1981, I went out to visit Mom and Dad. The three of us took a road trip through Northern California to see the Redwoods and other sights. Much to my surprise and delight, I still saw lots of open-wire there even at this relatively late date. On the flight back to New York, I had the good fortune to sit next to an older gentleman who was retired from the Southern New England Telephone Company. I began asking him questions about what he did with the intent of eventually bringing the conversation around to open-wire.

"Do you know if there is any open-wire left in Southern New England?" "Well, there might be pair or two here or there on private property--but essentially, no." We took all that stuff down years ago." I told him that I'd seen some around the University of Connecticut area in 1965, while visiting my older brother when he was in school there.

"Well, yes, back at that time there was still some there but that's been gone for sometime now," he replied.

I asked him about the large four or five arm line that I thought I'd seen the Wilton, Connecticut area in the 1950s when I was but a small child. I asked him if he knew what it was for or where it went?

"Well, I'm afraid I cannot recall a specific line like that at that particular location. But I can tell you that at that time we still had some lines like that, yes. But I don't remember tone in the Wilton area, I'm afraid. Could well have been, though."

When I asked him about the thing that had puzzled me for so many years. How as a small child I'd thought I'd seen a new shiny two-arm line while out with my Mom one day that I hadn't noticed before but later it was gone again. Had I really seen that or was my childhood memory playing tricks on me?

"Oh yes, that," he began with a slight chuckle. "I think I can explain that. You see, after the Second World War, there was a lot of new development in that part of Connecticut and we had a lot of new subscribers. Much of the area in those days was still quite rural. At that time, especially if ten or fewer subscribers were involved, it was our usual practice to hook them up to the nearest major cable line with open-wire. Then one day the decision was handed down from upper management to phase out the use of open-wire and we just took them all down again. Many lines had only been in service for a few years. There were quite possibly a few lines like the one you saw that had only been in service a few months. But we were told to phase it out so that's what we did."

I thought to myself, how incredibly bizarre! This whole explanation made me think of the kind of story I would've expected to come out of the old Soviet Union, but of course, I didn't tell him that. No matter. A small mystery that had piqued my curiosity for nearly 25 years was solved. In all probability, I had very likely seen exactly what I thought I'd seen as a four-year old child in the mid-1950's. That being the case, I began to wonder if my memory of the large multi-armed line in the Wilton area might also be accurate. It's just that throughout much of my adult life I was unable to pinpoint the exact location of the line for a long time.

Pouring over a DeLarme Gazetteer for Connecticut while fishing for memory fragments from the very depths of my brain from my very earliest childhood, I honed in on the Olmstead Hill Road area of North Wilton, CT. It seemed local that this place might fit my memory but how in the world could I ever know? This was such a long, long time ago. Enter the curator at the Wilton Historical Society.

I contacted her and explained my dilemma. She did some research in her archives and was not only able to locate a photo of the line, but two photos! I now have verification that the line really did exist and I didn't just dream this. Of course, it is still a puzzle to me as to what the line was for and where it went. Unless and until someone comes forward who remembers, I guess that will just have to remain an unknown. Perhaps some mysteries in life are just not meant to be solved.

I did not remain content doing music therapy in the Northeast for very long. In 1985, after five years of that, I changed careers and relocated to northeastern Indiana where I have pursued a 20-year vocation in the RV parts business. No open-wire here. Trust me. When I first moved to the area, there was still an occasional pair leading to a farm house or two, but even that's gone now.

With this we can conclude by reflecting back over the fact that the multi-arm, open-wire telephone line was once such a common and inseperable part of rural America has for all intensive purposes completely disappeared from the Nation's countryside. As of this writing (2006), it is perhaps still possible to find a few isolated one-arm lines in remote areas of the far West. But even if that is so, they are almost certainly living on borrowed time while the larger, multi-arm lines of yesteryear are long gone.

Wire antagonists may rejoice and bid good riddance to what they regarded merely as an ugly "eyesore" that only cast a blemish on the countryside. But I thin it's rather sad, really. I don't feel like they were ugly but instead, blended in well with the surrounding countryside and actually added something to it. In essence, they were a part of what we were.

This point is driven home in George R. Stewart's classic book, U. S. 40: A Cross Section of the United States of America, published by Houghton Mifflin, 1953. Although he might not have realized it at the time (or perhaps Stewart had an inkling), the author captured in words and photographs the very essence of cross-country motoring in the last years before the Interstate Highway System would forever change the way we travel.

Stewart's masterful photography also captured in black and white, some of the finest photographs I have found to date of rural, open-wire telephone lines. Professional photographers have historical gone to great lengths to make sure they cut wires out of their images. Not Stewart. He clearly saw what others couldn't see. The wires were part and parcel of his subject and not just merely something to get in the way to spoil it.

Using Stewart's own words from his forward titled, "As for this Book," he said, "A friend looked at one of the photographs and remarked, 'Very good! But it's too bad those wires came in where they did.' He was obviously speaking as one of the aesthetic school. I explained to him that far from trying to avoid the wires, I had maneuvered myself into a position where the wires were emphasized," Bravo! Professor Stewart, for a job well done!

Thomas and Geraldine Vale wrote a re-make of sorts of the Stewart classic volume in 1983, titled: U. S. 40: Thirty Years of Landscape Change, published by the University of Wisconsin Press in 1983. In their respective volume, the Vales would reprint Stewart's 1953 photo with their own underneath of the same location; hence a "before and after effect" was achieved.

In one great scene titled "Plains Border," Stewart had shown a two-lane, Portland concrete U. S. 40 section near the Smokey Hills section of Kansas. A beautiful, classic, four-arm toll line dominates this photo. Needless to say, the pole line had passed on by the time the Vales reconnected with the original Stewart scene. Furthermore, old U. S. 40 had been by-passed by new I-70.

As Vale puts it, "The decrease in the status of the roadway, which is now a Kansas (K-140) State Highway, would not explain the loss of the 'magnificent pole-line,' as Stewart described it, but the line's replacement, undoubtedly by underground cables, adds further to the feeling of isolation of the scene." Vale's succinct words pretty well sum up my own feelings. While it is difficult to deny the fact that new underground cables have almost certainly brought telephone users better service, none-the-less an unfortunate loss has occurred. Something that was once felt like an inseparable part of our landscape seems to be missing which, to those who remember open-wire lines, gives the countryside an increased feeling of "isolation."

Today, it is still possible to depart the Interstate and reconnoiter old U. S. 40 or U. S. 66 or a myriad of other older highways and by-ways. Once you're away from the hustle and bustle of the city and suburbs, you can still view a landscape that is not too much different from the one Stewart knew. Many of the pastoral settings are still there. Many of the tidy, rural farmsteads are still there. The breathtaking western scenery is certainly still there. But the quaint, rural telephone lines that added their own colorful charm to these scenes are gone.

What is beyond sad--in fact, down right tragic--is that this could all happen with nary a word. There was no write up in TIME, LIFE or Newsweek magazines of their passing. There was no "three-minute" On the Road ditty shown as a tribute by Charles Kuralt on the CBS Evening News. No . . . the lines just quietly departed the landscape, that's all. This is a most unfortunate set of circumstances that needs to be set right. Perhaps . . . there is still time to do that.

Part II: The Causes of Demise

It is most certainly justified to ponder over the question as to what caused the demise of the rural open-wire telephone line. How in the world could something once so commonplace, so utterly and completely disappear from the landscape during the course of one man's short lifespan? It would be tempting to simply dismiss open-wire as an old-fashioned "has been," which was nothing more than an obsolete, older technology. However, the true reason for the demise of open-wire is more complicated and subtle than that. The fact is, the cause of open-wire's demise had as much to do with simple, old-fashioned economic principles as with changes in technology.

To address this question, we need to first take a look at what made open-wire popular in the first place. Prior to around 1940 or 1950, there were two primary factors making open wire highly economical in rural areas. First of all, the lead-sheathed cables in vogue during the open wire era were costly to manufacture and to maintain. They had a superior advantage over open-wire in they could contain hundreds of individual circuits. This fact made the lead-sheathed cable both practical and a down right necessity in large urban areas.

But, the fact remained in rural areas where perhaps 30 or fewer pairs were required, open-wire was cheaper to maintain than lead-sheathed cable. A second factor in the economics of open-wire was by the very nature of its larger diameter wire, it could transmit a signal much farther than the very fine, thread-sized wires of a cable before amplification became necessary. Early amplifiers with their hand-soldered circuits and vacuum tubes were also quite salty to acquire and were maintenance intensive. Both of these factors made open-wire economically attractive in areas where less than 25 or 30 pairs were required and the signals had to be transmitted over considerable distances.

The development of cheap, polyethylene-sheathed cable along with the printed circuit board and transistors, caused open-wire to completely lose the two primary economic advantages that it had possessed over cables. Polyethylene cable had an additional advantage in that it could be buried directly in a trench without requiring expensive conduits. This allowed telephone companies to dispense with wooden poles completely in some instances.

Two smaller factors contributing to the end of open-wire counted the decline of the rural party line and the complete demise of the magneto telephone. Fifty years ago, many rural lines had as many as eight parties on a line. A two-arm, ten-pair open-wire line with eight parties per circuit could therefore service up to eighty subscribers. In many sparsely populated areas, 80 subscribers might be spread over a considerable distance. That, in turn, caused the two economic advantages discussed previously to perpetuate the use of open-wire. In our modern "at-your-fingertips" world, the party line has largely disappeared as most people desire and expect privacy.

The older technology employed in magneto telephones was also a lot more forgiving of the transmission interference problems found on open-wire lines such as wet, clinging snow which accumulated around insulators, or wet tree branches hanging in the wires. When rural telephone companies wet to direct dialing, they soon discovered that open-wire lines had to be strictly maintained to the very highest levels or the results were mis-rings and ringing failures. This merely provided yet another incentive for rural telephone companies to do away with open-wire. All of these developments took place during a time when labor costs were generally rising along with the cost of materials required to build and maintain open-wire. Open-wire quite simply--priced itself out of existence.

One might be quick to assume the development of modern fiber optics cable played a major role in the demise of open-wire. But in reality, fiber optics had little or now impact because by the time fiber optics became economically feasible, most open-wire telephone lines were already gone.

Revival?

To the die-hard, open-wire enthusiast or insulator collector, it's fun to contemplate the notion as to whether or not open-wire telephone lines could perhaps one day stage a comeback. While such a possibility seems extremely unlikely at best, neither can it be entirely dismissed as completely impossible.

Polyethyline is derived from petrochemicals. Petroleum is anon-renewable natural resource. Once it's gone--it's gone. Anyone forced to pay today's prices at the gas pump is all too aware of this fact. If costs rise too far, such materials could be uneconomical again. On the other hand, the wood used in poles and crossarms is a renewable natural resource. Glass insulators are made from silica sand. Hardly a chance of ever running out of sand and glass can be recycled anyway. That only leaves the wires. But, perhaps new materials could also be developed to make new wires with, possibly through the use of nanotechnology. Could changing economics once again tip the balance back to favor open-wire? The plain and simple fact of the matter is yes . . . it could.

Rising technology, while contributing to the demise of open-wire, can also work to its benefit. It is probably an ironic fact that advancing technology during the 1930's and'40's and '50's, almost certainly extended the lifetime of many open-wire lines. New kinds of carrier systems allowed a huge increase in the capacity of existing open-wire lines without actually requiring the addition of any new wires. But, as open-wire cost rose and cable costs fell, in the end, even those advanced technologies were unable to save open-wire lines.

A 1952 AT&T Bell Labs' advertisement touting newly developed "O-Carrier," which appeared in many periodicals of the period, exemplified the extended working lives of many existing older long distance open-wire toll lines.

Taken to a much higher level, especially if rising cable costs become a major issue, new, highly advanced technologies could play a role in a comeback. Some modern digital mixers, for example, can allow as many as 192 simultaneous messages, including Internet, to be transmitted over a mere eight pairs of wires. Could open-wire be employed in such a technology? I believe such a possibility should at least be considered and researched by modern telecom companies--if for no other reason than open-wire is yet quite common in much of the developing world.

It is clear there are huge obstacles to such a revival in America. For one thing, the manufacture of parts needed in ope-wire lines--everything from glass insulators, pin, arms and transposition brackets ceased long ago. More importantly, the tooling necessary to make those items is probably gone. Another regrettable loss is the American "know how" of stringing and maintaining open-wire lines is probably no longer available.

There is, however, another way that open-wire might make a comeback. That could happen if open-wire enthusiasts and insulator collectors simply take things into their own hands and build their own lines. The increased interest of recent years on the part of insulator collectors and open-wire enthusiasts has give rise to what I like to call the "backyard telephone line." A backyard line can be an excellent way to illustrate how older open-wire lines appeared and display an insulator collection at the same time. Across the land, a number of talented individuals have crafted such lines.

One final thought on the subject of open-wire might be to plan some kind of a large, indoor/outdoor telephone museum. There are already a number of excellent telephone museums around the country. However, with real estate at a premium, it is difficult for most of these museums to adequately display and represent outdoor plant and equipment.

It would be nice if we might envision a telephone museum that could be located on around one hundred to three hundred acres or so in a rural setting situated conveniently near a major state or Interstate highway. Perhaps such a museum could combine forces with a railroad museum accessing expansive acreage. Such facilities would represent typical facilities--some designed to be functional as well.

I believe the memory of these quaint, historic and once important lines should be preserved for future generations. Open-wire enthusiasts and insulator collectors have a unique advantage to help make this happen due to their vast knowledge, their enthusiasm for the subject, not to mention their extensive collections of insulators. The help and hard work from collectors will be necessary to keep the memory of our Nation's open-wire telephone facilities alive. Wouldn't it be wonderful for future generations to be able to say of open-wire telephone lines: "Gone but not forgotten."

[Webmaster's note: see within this website the chapter on preserving the first open-wire lead and its in situ location along I-90 near Tilford, South Dakota by this webmaster. Additionally, The Electric Orphanage of North America, Inc., a 501(c)(3) non-profit is in the process of obtaining land for doing just as emphasized in the above article: a continental museum of not only early open-wire telephone beginnings but of electric power T&D and outdoor lighting.]